What is a best practice for linking Just-In-Time Tasks?

Yes, absolutely.  Years ago I did a couple of training classes for two groups of project managers at NASA.  When we talked about the SF dependency, they described how the launch of a rocket is a "sacred event", whose date and time are "etchec in store" so to speak.  They have a final milestone in their projects that represents the date and time of the launch.  Then the final sequence of activities that must be performed before the launch are all linked from the launch milestone backwards using the SF dependency.  So, your use of SF is reasonable, given the situation you describe.  As an aside, when I finished my classes with the NASA project managers, I asked them how I could volunteer for the first manned mission to Mars.  And they all laughed at me!  This was LONG before Elon Musk and SpaceX, by the way.  HA!